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The chunk of ice that broke off from the Ward Hunt Ice Shelf on Aug. 18 is circled in the above image. The ice shelf extends from the northern coast of Ellesmere Island, which is visible in the bottom two-thirds of this satellite image. ((NASA/GSFC, MODIS Rapid Response))

A large parcel of ice has fractured from a massive ice shelf on Ellesmere Island in Nunavut, marking the third known case of Arctic ice loss this summer alone.

The chunk of ice, which scientists estimate is roughly the size of Bermuda, broke away from the Ward Hunt Ice Shelf on the island's northern coast around Aug. 18, according to NASA satellite imagery.

At 40 metres thick, the Ward Hunt Ice Shelf is estimated to be 3,000 to 5,000 years old, jutting off the island like an extension of the land.

"The cracks are going right to the mainland, basically, right to Ellesmere Island," John England, a professor of earth and atmospheric sciences with the University of Alberta, told CBC News on Tuesday. "So, in the core of the ice shelf itself, the fracturing is occurring.

"I think that's really quite significant, that it's like the most resistant and most tenacious part of the ice shelf is now being dismantled."

Giant tracts of Arctic ice have been calving off ancient glaciers and ice shelves in recent weeks.

On Aug. 5, a 251-square-kilometre "ice island" broke from the Petermann Glacier on Greenland's northwestern coast, making it the largest iceberg to form in the Arctic since 1962.

A smaller iceberg broke off the Jakobshavn Isbrae glacier in Greenland in early July.

Ice loss season not over

The Ward Hunt Ice Shelf is one of six ice shelves that have extended 450 kilometres along the north coast of Ellesmere Island.

According to the Canadian Ice Service, the Ward Hunt Ice Shelf cracked in half in 2002. However, the two pieces somehow stayed in place, possibly held together by the island of the same name.

In 2008, further large cracks were found in the Ward Hunt Ice Shelf, which by then had lost about 10 per cent from its seaward margin.

Of the other ice shelves along Ellesmere Island, the Ayles Ice Shelf broke away completely in 2005, creating an "ice island" that drifted south into the Canadian Arctic archipelago.

About 33 per cent of the Petersen Ice Shelf has eroded away between 2005 and 2008.

Sixty per cent of the Serson Ice Shelf broke into small pieces in 2008 while the entire Markham Ice Shelf broke away that same year.

England said there is still a month to go in the summer ice loss season in the Arctic Ocean, raising the possibility that other parts of the Ward Hunt Ice Shelf — particularly on the eastern side — could easily break off.